Pressure relief valves are used in a variety of commercial, industrial and domestic applications to maintain a pressure within a container below a predetermined maximum pressure. Specifically, if the pressure within the container exceeds a start-to-discharge pressure or predetermined maximum pressure, the pressure relief valve will vent a fluid or vapor to the atmosphere until the pressure within the container decreases below the predetermined maximum pressure. The amount and rate at which the fluid or vapor is vented to the atmosphere is associated with the magnitude of the pressure within the container.
Different pressure relief valves have different sizes, start-to-discharge pressures and flow capacities. A pressure relief valve may be selected for use with a container based on a design specification of the container such as a maximum pressure to which the container can be safely exposed without rupturing.
Known pressure relief valves often include an actuator having a spring that exerts a force on a shaft to urge a valve seat towards a seating surface. In practice, if a plurality of pressure relief valves is used with a manifold assembly, each of the plurality of pressure relief valves is at least partially positioned within one of a plurality of tubes coupled to the manifold assembly. Typically, each tube is substantially the same length as the pressure relief valve and is made of a metal material and, thus, the length and weight of the pressure relief valve drastically impacts the overall weight and size (e.g., height) of the manifold assembly.
Multiple pressure relief valve manifolds are used particularly in propane, natural gas, and anhydrous ammonia storage tanks. These manifolds typically include four pressure relief valves that are fluidly connected to the manifold. A selection mechanism selectively disconnects one of the pressure relief valves from the manifold at a time for testing, periodic maintenance, and/or replacement. Multiple pressure relief valve manifolds are typically large, heavy, and prone to leakage at the connection between the pressure relief valves and the manifold.